Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) (Interest Rate Swap Agreements [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013 Caontracts	Dec. 31, 2012 Caontracts
June 2013 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	0	2
Notional amount	$ 0	$ 85,000
Mandatory cash settlement date	0	June 2013
October 2014 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	2	2
Notional amount	50,000	50,000
Mandatory cash settlement date	October 2014	October 2014
October 2015 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	2	1
Notional amount	45,000	25,000
Mandatory cash settlement date	October 2015	October 2015
October Two Thousand Sixteen [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	1	0
Notional amount	$ 20,000	$ 0
Mandatory cash settlement date	October 2016	0